Optimizing the Ratio of Metallic and Single-Atom Co in CoNC via Annealing Temperature Modulation for Enhanced Bifunctional Oxygen Evolution Reaction/Oxygen Reduction Reaction Activity

Developing low-cost, efficient alternatives to catalysts for bifunctional oxygen electrode catalysis in the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) is critical for advancing the practical applications of alkaline fuel cells. In this study, Co particles and single atoms co-loaded on nitrogen-doped carbon (CoNC) were synthesized via pyrolysis of a C3N4 and cobalt nitrate mixture at varying temperatures (900, 950, and 1000 degrees C). The pyrolysis temperature and precursor ratios were found to significantly influence the ORR/OER performance of the resulting catalysts. The optimized CoNC-950 catalyst demonstrated exceptional ORR (E1/2 = 0.85 V) and OER (Ej10 = 320 mV) activities, surpassing commercial Pt/C + RuO2-based devices when used in a rechargeable zinc-air battery. This work presents an effective strategy for designing high-performance non-precious metal bifunctional electrocatalysts for alkaline environments.